#include<stdio.h>
int main()
{
    int arr[] = {1,2,3,4,5,6,8,7,10,11,12};
    int k = 12;
    int sz = sizeof(arr)/sizeof(arr[0]);
    int left = 0;
    int right = sz-1;
    while(left<=right)
    {
        int mid = (left+right)/2;
        if(arr[mid]>k)
        {
            right = mid-1;
        }
        else if(arr[mid]<k)
        {
            left = mid+1;
        }
        else
        {
            printf("找到了，下标是：%d\n",mid);
            break;
        }
    }
    if(left>right)
        {
            printf("找不到了\n");
        }
    return 0;
}